UN Secretary-General Ban Ki-moon, a former South Korean Foreign Minister, is due to step down at the end of 2016 after serving two five-year terms. The job customarily rotates between regions, with Eastern Europe next on the list.

"With her biography and experience Bokova can be one of the major candidates in the upcoming campaign for the U.N. Secretary General," the Bulgarian foreign ministry said in a statement yesterday.

Before taking the post at UNESCO in 2009, Bokova, 63, serve as extraordinary ambassador to France in 2005 and as acting Foreign Minister in a Socialist government in 1990s.

The United Nations formally kicked off the race for the next secretary-general in December and the world body's 193 members were encouraged to put forward women candidates. The post has been held by men for the past 70 years.

So far, other nominees include former UN General Assembly President Srgjan Kerim of Macedonia, Slovenian former President Danilo Turk and former Portuguese Prime Minister and ex-UN High Commissioner for Refugees Antonio Guterres.